<div>
  <span>Loading …</span>
</div>

<style>
div {
  display: table;
  text-align: center;
  color: rgba(0, 0, 0, 0.3);
  font-size: 12px;
  line-height: 100%;
  height: 100%;
  width: 100%;
}
span {
  display: table-cell;
  vertical-align: middle;
}
</style>